Production of carbonate esters



Patented Aug. 8, 1950 PRODUCTION OF CARBONATE ESTEBS Alphonse Pechukas,Akron, Ohio, aseignor to Pittsburgh Plate Glass Company, AlleghenyCounty, Pa., a corporation oi Pennsylvania No Drawing.

Application January 2, 1947, Serial No. 719,927

a 6Claims. (01.280-463) .This invention relates to novel carbonateesters and to novel methods of preparing carbonate esters.

In accordance with the present invention it has been found thatcarbonate esters of Beta halo alcohols may be prepared by reacting ahaloformate with an epoxide, in which the oxygen atom is linked toadjacent carbon atoms and therefore contains the group o R0CX ,J n

l where R, is the radical of the alcohol ROH, X is halogen such aschlorine or bromine and l is the epoxy oup of the epoxy compound.Various isomers of the halo esters are formed. Thus when butadienemonoxide (1.2 epoxybutene-ii) is reacted with a haloformate such asethyl chloroformate, mixturesrof ethyl chloromethylvinylca-rbinylcarbonate and ethyl 2-chloro-3- butenyl carbonate are produced.

The carbonate esters obtained in accordance with this invention usuallyare stable liquids which haverelatively high boiling points. Many ofthese unsaturated esters polymerize in the presence of ultra violetlight, peroxypolymerization catalysts such as benzoyl peroxide, lauroylperoxide, acetone .peroxide, or other oxygen poly merization catalystsuch as oxygen, ozone, etc.,

- esters.

to form solid polymers. This is especially true of the esters formed byreaction of an unsaturated epoxide with an unsaturated haloiormate.Generally such polymers are less inflammable than most of the polymersof unsaturated carbonate These esters also may be copolymerized withother unsaturated compounds such as styrene, vinyl acetate, vinylchloride, methyl methacrylate, allyl or methallyl esters of polybasic orunsaturated acids such as diallyl phthalate, allyl methacrylate,ethylene glycol maleate, etc. The carbonate esters also may be used asintermediates for the .production of other compounds. For example theymay be chlorinated to produce high boiling liquid esters which may beused as plasticizers.

Saturated halo esters obtained by reaction of a saturated chloroiormatewith a saturated epoxide generally are high boiling liquids capable ofuse as plasticizers and heat exchange media.

The process herein contemplated may be performed by mixin the epoxidewith the haloiormate and permitting the reactants to interact. The rateof reaction is improved materially when catalysts such as pyridine,quinoline, isoquinoline, triisobutyl amine or other tertiary amine,aluminum chloride, ferric chloride, zinc-aluminum chloride mixtures andother Frledel-Crait catalysts, are used.

During'the process, heat is evolved and where the reaction is conductedupon a substantial scale, cooling generally is necessary in order toprevent overheating. Usually the process is performed at temperatures of0 to 125 C. Elevated temperatures, at least in the initial stages ofreaction, usually are undesirable due to the tendency for chloroformatesto decompose at such temperatures. Consequently the initial temperatureof reaction usually is maintained below about 50 C. Solvents may bepresent if desired in order to facilitate contact 01' the reactants. Forexample, an initial content of the ester to be produced may be used as amutual solvent for the reactants. Other solvents such as acetone,chloroform, benzene, toluene, xylene, etc., may be I used if desired.The presence of large amounts of water is undesirable in view 01' thetendency acraoea the corresponding Beta halo alkyl esters of carbonicacid. Other esters may be prepared by .re-

acting haloiormates with cycloaliphatic or aromatic epoxides such asstyrene oxide, cyclopentene oxide or cyclohexene oxide or withsubstituted epoxides such as epichlorohydrin, glycidol, glycldol ethersor esters such as glycidol ethyl ether, glycidol allyl ether, etc.

The invention is particularly concerned with the esters which may besecured by reaction of haloiormates with epoxides oi dioleflns such asbutadiene monoxide, butadiene diepoxide, butadiene dimer epoxide(4-vinyl-l,2 e9 cyclohexane) butadiene dimer diepoxide, chloroprenemonoxide or isoprene monoxide or the epoxides of dimers and trimers oiisoprene or chloroprene or of cyclopentadiene.

Carbonates of unsaturated halo alcohols are secured by reaction ofhaloformatea or diene monoxides'. Such unsaturated carbonates usuallypolymerize in the presence of ultraviolet lizht ozone or peroxycatalysts such as benzoyl peroxide to form resinous products.v Whendiepoxides of dienes such as butadiene diepoxide or butadiene dimerdiepoxide are reacted with haloformates 3o such as ethyl chloroi'crmate,high boiling liquids which are dihydric alcohol-bis (monohydric alcoholcarbonates) and which are useful as plasticizers for plasticcompositions such ascellulose acetate, ethyl cellulose, polyvinylchloride, polyvinylacetate, polystyrene, polyvinylidene-chloride. etc.

The process may be carried out using numerous haloiormates includingaryl, alkyl, alkenyl and alkynyl haloiormates such as the chloroiormatesof methanol, ethanol, isopropanol, isobutanol, npropanol, octyl alcohol,lauryl alcohol, allyl alcohol, methallyl alcohol, 2 chloroallyl alcohol,crotyl alcohol, propargyl alcohol, benzyl alcohol or phenol. Moreoverdich oroformates such as the dichloroformates of ethylene glycol,diethylene glycol, triethylene glycol, etc., ma be reacted with theabove 1,2 epoxy compounds.

The practice oi the invention will be apparent from the followingillustrative examples.

Example 1 Ethyl chloroiormate, 54.3 grams, was placed in a three-neckflask, provided with.a dry ice-acetone cooled reflux condenser. Fortytwo grams oi' 1,2-epoxybutene-3 was added slowly to the chloroformate atroom temperature. During this addition very little reaction took placeup n-addition of 0.9 gram of pyridine to the mixture, 1:.

. violent reaction occurred accompanied by vigorous and the mixedcarbonate of ethyl alcohol and lchloro-3 butenol-2 having the probablestructure the former ester being predominant. This product 18 a liquidhaving a boiling point 0! 85-88 C.

ate millimeters pressure and an index oi retractionn ==l.44l4.

8 lizamplc Z l lethyl ehloroiormate, pyridine and ethylene I oxide weremixed in a reactor at 0 C. in the proportion of 9.5 grams of methylchloroiormate per m 4.4 grams of ethylene oxide and 0.5 gram ofpyridine, the pyridine being added to the mixture of chloroi'ormate andepoxide. The reaction was Provided with a reflux condenser cooled with adry ice-acetone mixture. After the mixing was complete the mixture wasallowed to stand at room temperature overnight. Thereafter the reaetion'mixture was ira'ctionated and methyl 2- chloroethyl carbonate wasobtained. This ester has the probable structure oni-o-o-oomcmoi Thisester was a liquid distilling at 85-6 c. at

38 millimeters pressure and having an index voi refraction n '=1.4275.

Example 3 ;Diethylen e glycol dichloroformate, 57.8 grams,

was introduced-into a three neck flask which was provided with a stirrerand a water cooled reflux 14.5 grams of propylene oxide was added to thediethylene glycol dichloroiormate and then one cubic'centimeter ofpyridine was added and. the mixture stirred vigorously. Thetemperatureroee to 35-40 C. and the temperature of the mixture wasmaintained at this level by cooling using an ice bath. An additional14.5 of propylene oxide was added and stirring was. continued for fourhours while maintaining the temperature of the mixture at 35-40? C.

Heating was required for the last three hours to maintain thistemperature. The mixture then was allowed to stand overnight and afterstandhis was dissolved in 200 cubic centimeters of carbon tetrachloride,washed three times with 5 dilute sulphuric acid to neutralize thepyridine and the neutralized product was fractionated and a water whiteliquid ester which is diethylene glycol bis (chloropropyl) carbonate wasobtained. This ester distills at 200-210 C. at 3.5 millimeters A wpressure and has an index of refraction a of 1.4612: Ethylene oxide maybe used in lieu of propylene oxide and the same results obtained ifpressure is maintained upon the reaction mixture to prevent escape orthe ethylene oxide during 5 the process.

Example 4 The process of Example 3 was repeated using 60.1 grams ofstyrene oxide, 54.3 grams of ethyl The ester is a water white liquidwhich boils at 135-140" C. at 4 millimeters pressure and which has anindex of refraction 11, of 1.5078.

Example Epichlorohydrin 92.5 grams was reacted with 108.5 grams of ethylchloroformate in the presence of two grams of pyridine in an apparatusof the type described in Example 3. Addition of the epichlorohydrinrequired about one hour. The mixture was stirred and was maintained at45-55 C. during the addition and for five hours thereafter. Uponfractionation a colorless liquid carbonate ester, which is ethyldichloropropyl carbonate was obtained. This ester boiled at 83-86 C. at4 millimeters pressure and had an index of refraction 12 of 1.4562.

The above described processes may be conducted using other haloformatessuch as the corresponding bromoformates to produce the correspondingbromo esters.

Although the present invention has been described with reference to thespecific details of certain embodiments thereof it is not intended thatsuch details shall be regarded as limitations upon the scope of theinvention except insofar as included in the accompanying claims.

What is claimed:

1. A method of preparing a carbonate ester which comprises reacting a1,2 epoxide with an ester of an haloformic acid.

2. A method of preparing a carbonate ester REFERENCES CITED Thefollowing references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,370,571 Muskat et a1 Feb. 27,1945 2,370,589 Strain et a1 Feb. 27, 1945 2,385,933 Muskat et al. Oct.2, 1945 2,395,070 Sarbach Feb. 19, 1946 OTHER. REFERENCES Bedos,"Comptes rendus (Paris), vol. 183, pp.

1. A METHOD OF PREPARING A CARBONATE ESTER WHICH COMPRISES REACTING A1,2 EPOXIDE WITH AN ESTER OF AN HALOFORMIC ACID.